The present invention relates to valve mechanisms for controlling the discharge of material under pressure from a container. In particular, the invention relates to discharge valves for fire extinguishers.
There are present in the prior art many container closures and dispensing devices designed to operate with fluids or free-flowing powders which are under pressure, such as fire extinguishers. Such dispensing devices have also been provided with pressure indicating means to give an indication of the pressure within the container so that a user can tell whether the container needs to be repressurized or refilled. However, such prior dispensing devices with pressure indicators are typically of complex construction, comprising a large number of parts. In many cases some of these parts or portions thereof are exposed in use, so as to be subject to the environment in which the fire extinguisher is used or stored. Furthermore, in those devices in which the indicating means forms a part of the valve mechanism, it typically entails elongation of the valve mechanism and, therefore, the housing thereof, thereby increasing the overall size of the extinguisher.